Telegraph system



.I. H. BELL.

TELEGRAPH SYSTEM.

APPLICATION FILED/APR. 9. I918.

1,387,229. Patented Aug. 9, 1921.

JOHN H. BELL, 0E sourn: oEAneE, -1\TEW JERSEY, Ass r'enoElT-o WESTERNELEcrnrc comrnnr, INCORPORATED, or NEWMYOIRKIV. A CORPORATION or NEWYORK.

TELEGRAPH SYSTEM.

Application filed April 9,

' To all whom it may concern:

Be it known that I, JOHN H. BELL, a citizen of the United States,residing at South Orange, in the county of Essex, State of New Jersey,have invented certain new and useful Improvements in Telegraph Systems,of which the following is a full, clear, concise, and exact description.

This invention relates to telegraph sys? tems and more particularly totelegraph transmitting systems.

An object of this invention is to'provide an effective and reliableremedy for the socalled wandering zero effects commonly experienced inconnection with telegraphic service over conductors having highelectrostatic capacity, such as long land lines or cables and submarinecables.

Another object is to provide a remedy for leakage effects on telegraphcircuits as usually causedon open wire lines due to dampness or wetweather conditions, the term leak nullifier being commonly employed inthe art in. referring to arrangements for overcoming such leakageefiects.

In accordance with the present invention thereis provided an arrangementwhereby an impulse of clearing current having a polarity opposite to thepolarity of a preceding signaling impulse will cause a properopposing,neutralizing or current balancing effect in the hue circuit.

v This invention is illustrated diagrammatically in the accompanyingdrawing in which for the sake of clearness only so muchof av telegraphsystem has been shown aswill be necessary to a clear understanding ofthe invention;

In Figure 1 there is shown a terminal equipment for a telegraph linecircuit which consists of a single line c'onductor and the usual earthreturn, arranged in" a manner suitable for carrying out the features ofthis invention' In F ig. 2 there is shown an arrangement similar to thatshown in Fig. 1 except that the terminal" equipment provides foroperation over a metallic telegraph circuit formed of two lineconductors.

I Fig. 3 illustrates the theoretical effects of current impulses in atelegraph conductor in which no provision is made for clearing orcompensating for the :usual wandering zero effects, while in Fig. 4ofthe drawing, there a is shown a theoretical condition of the cur-Specificationof Letters Patent, 7 Patented Aug. 9, 1921.

1918. SerialNo. 227,567.

rentsin a telegraph conductor on which the ero balancing and the leaknullifying fea tures of the present invention have been applied.

v Aline conductor 1 (Fig. 1) extends from a distant station (not shown)through the windlng of a line relay2, the contacts 4 of a telegraph key3 anda line battery 6, to

earth.- The battery 6 is also connected over. i

contacts 5 ofvthe key 3through the winding of a relay 7 and a resistance10, to earth. In transmitting signals from the present statlon, the key3 may be operated in the usual manner- At eachclosure of the contacts 4Lof this key the battery 6 will be connected in series with the relay2,'t0 the line conductor 1. 5 Contacts. controlled by the linerelay 2will be understood as arranged for the control of a reading sounder orother suitable telegraph receiving device. In addition to connectingthebattery 6 with the line conductor, eachclosure of the key 3 alsoconnects this battery through the. local relay 7 as already described.Energization of'this relay connects a battery Il1 over the'relaycontacts 8 to charge a condenser 12'. The batteries :6 and-11 are ofopposite pOlarities.

Therefore, when the key 3 is released to separate its contacts 4: and 5,in addition to cessation ofcu'rrento-f the battery 6 to the" lineconductor 11, the relay 7 is released to separate its contacts8 andestablish its normal contacts 9. This action of the. relay connects thecondenser12 in derived'relation tothe line conductor 1, causing thecondenser to discharge and-send to line 1, an impulseof a'polarityopposite .to-that of the preceding signaling impulse fromjthe negativebattery 6.

Referrlng to straight line A represents the true Zero potential point:of the line conductor, while the solidline Brepresents the theoreticaleffectof current impulses. at the transmitting end oft-he line circuitand reading from left to rightgcorrespond with two dots, a dash-and aspacing interval: fThe dotted curved line C represents theoretically,the shape of, current waves at a distantor receiving station on theline, circuit, the electricalcharacteristics of the line havingtransformed or distorted the current waves B into the condition in whichtheyare shown by this line C. The current line G, as the'impulses,c'ontinueto be trans- F ig. 3 of the drawing, the I i Fig. 3, while thesolid line D corresponds with currents set up at the transmitting-end ofthe line by the discharge action of the condenser 12. The dotted line Cshows the shape of the resulting wave at a distant receiving stationafter it has been transformed or reshaped due to the electricalcharacteristics of the line, as well understood in the art. The currentwave C in this figure of the drawing corresponds with the shape of areceived current wave, the transmitted impulses forming which have beenacted upon by the current clearing or comoensating effects as applied bythe presentinvention. This resultant current wave,-

in addition-to showing a better definition between impulses, alsocontinues substan tially balanced with respect to its current values onthe respective positive and negative sides of the true zero line A.

Referring to Fig. 2 of the drawing, this alternate arrangement is ingeneral similar to the first arrangement already described except thatthe line relay is provided with two coils respectively indicated as 2and 22, while additional contacts 28 and 29 are provided for the relay7. In tracing a circuit through this terminal equipment, the first lineconductor 1 incoming from a distant station is connected through thecoil 2 of the line relay, thence through the telegraph key 3, the linebattery 6 and the second winding 220i the line relay, to the lineconductor 21 which also extends to the assumed distant station. Intransmitting message impulses from this station the key 3 con trols theinclusion of the battery 6 in series relation with the line conductors 1and 21 over the circuits already traced. At each closure of thetelegraph key, in addition to establishing the line'circuit through itscontacts t, its contacts 5 also complete a circuit through which currentfrom the battery 6 may traverse the resistance unit 10 and the windingof the condenser control relay 7.

-During the time the relay 7 is energized current from the line battery6 is connected over the contacts 8 and 28 of this relay 1n forming acircuit to charge the condenser 12. On the key 3 being released toseparateits contacts 4: in disconnecting the battery 6 from the metallicline circuit, sepa ration of the key contacts 5 also disconnects relay7, are such that the condenser will be charged in opposite polarityrelation with respect to the current impulses, from'the battery 6 to theline circuit. Therefore, at the instant the relay 7 is disconnected thecondenser 12 will discharge over the metallically connected lineconductors in a direction'opposite to thatof the signaling currents overthese conductors.

As indicated in the drawing, thelresistance 10 and condenser 12 may beof variable types and the potential of the battery 11 may also bevaried. In this manner a circuit relation may be obtained whereby therelatively short current interval present when the condenser 12discharges would be such that the residual current remaining in the linecircuit following a signaling impulse would be suitably counteracted orneutralized by the current from the condenser. Such condition ofbalancewould result in securing the well defined current line' C as shown inFig. 4: of the drawing.

In describing the manner in which the present system may fulfiltherequirements of a leak nullifier, let it be assumed that the line 1(Fig. 1) is routed through several intermediate or way-stations, thencethrough a distant terminal station at which a line battery similar to,but oppositely poled with respect to the line battery 6, is included inthe circuit in the same manner as the battery 6. It will, therefore, beclear that during such time as the line circuit may be idle, thebatteries at the remote stations form an accumulative series to retainall of the line re-.

sulation may be present due to wet Weather along the route of the linecircuit, it now the key 3 is opened as in the operations of sending amessage the battery 6 will stand disconnected and the home relay 2 willbe re leased. It will be obvious that thepositively poledbattery at thedistant end of the line may then continue to flow outwardly over thelinecircuit and through the various relays at the way-stationsinproportion to the leakage present along the line conductor. This currentwill havea tendency to retain the armatures of the line relays at theway-stations and at the distant terminal station irrespective of theopen moments of the key 3 at the present terminal station. As a remedyfor this condition as applied by the present invention, it will be clearthat on the key 3 being released to disconnect the relay 7, a dischargefrom the condenser 12 outwardly over the line circuit 1 will be inopposite phase or differential with respect to the line battery at theremote terminal station, thereby causing a sufficient cessation in flowof current from the distant line battery to permit the relays at' theway-stations and the distant terminal station to release. In a conversemanner, the employment of equipment at the distant terminal stationsimilar to that shown in the drawing will serve as a remedy for lineleakage when messages are being sent from that station in a mannersimilar to that described for the transmission of messages iron thestation shown in Fig. 1.

Referring to Fig. 2 of the drawing, the equipment for metallic circuitworking shown therein may also act as a remedy for line leakage troubleswhich may occur from the metallic circuit formed of the line conductors1 and 21. Inthis arrangement it will be understood that the line relaysat the intermediate stations may be connected inseries with the lineconductors in the same man ner as the line relay coils 2 and 22 and thata similar but oppositely poled battery may be serially connected in theline loop at a distant terminal station to normally form an accumulativeseries with the line battery 6. Operation ofthe key 3 in controlling thetransmission of impulses and also working the relay 7 to establishcounter electromotive forces, results in the condenser 12 momentarilyopposing the battery of the distant terminal station, thereby causing acorresponding cessation of current from that battery over the leakagepresent along the line circuit. In this manner, the relays at-theintermediate stations and also at the distant terminal station may bereleased and therefore conditioned to respond to the key?) irrespectiveof the leakage condition of the line circuit, this remedy beingeiiective from the distant terminal station when messages may be undertransmission therefrom in a manner similar to that described inconnection with the present station;

Although .the arrangements shown and described appear to constitute apreferred embodiment of this invention, it will be understood thatvarious departures from this embodiment may be made without departin gfrom the spirit of this invention.

What is claimed is: s

1. In a telegraph system, a line circuit, equipment comprisingtransmitting and receiving devices and a source of current seriallyconnected wtih said line circuit for the handling or" message impulses,a condenser, a relay for respectively including said condenser in bridgeof said source of current or in bridge of said equipment, and meansoperated by said transmitter for controlling the operation of saidrelay.

' '2. In a telegraphsystem, a'circuit formed of two line conductors,'atelegraph transmitter and a source of current serially connected withsaid line conductors for the transmission of message impulses, acondenser, a relay ior respectively including said condenser in bridgeon said source of current or in bridge on said line circuit, and meansoper-.

ated by said transmitter for controlling the periods said source ofcurrent may be disconnected from the line.

a. A telegraph system comprising a line,

a source of current, a condenser normally connected with said source ofcurrent, a transmitting key, and a relay controlled by said transmittingkey and adapted upon its deenergization to connect said condenser withsaid line whereby a current impulse of a polarity opposite to that ofthe line current present atthe remote station traverses said line. r I I5. In a telegraph system, a metallic line circuit "formed by twoconductors, a terminal station comprising a receiving means, atransmitting means and a source of line current included in series withsaid line conductors, intermediate stations comprising receiving andtransmitting devices connected tical with the station described, atwhich the line battery is connected to form an accumuloo seriallywithsaid line conductors, a distant terminal station equlpped' in amanner ideniative series with the line battery at the first terminalstation, a condenser'and a relay at each terminal statlon, and meanscontrolled by the ZLSSOOlfiiZGd tl'ELHSHllttGI for rendering said relayeffective to respectively 3 connect said condenser to be charged fromthe associated source of current or to dis- I charge in series with saidline conductors in opposite polarity relation with respect to the linebattery at the-distant terminal station.

6. In a telegraph system, a line conductor, a terminal stationcomprislng receiving and transmitting devices, and a source of currentconnected serlally with said llne conductor,

intermediate 1 stations comprising receiving 7 and transmitting devicesconnected serially with said line conductor, a distant terminal stationcomprising equipment identical with the equipment described at which thepolar- .ity of the line battery is such that an accumulative series willbe formed between the batteries of the terminal stations, a condenserand a relay at each terminal station, means controlled by said relay forconnecting said condenser to receive a charge from the associatedbattery, means operated by a terminal transmitter for controlling theassociated relay, and means controlled by said relay for connecting saidcondenser to discharge over said line circuit in opposing polarityrelation with respect to the line 10 battery at the distant terminalstation. n

In Witness whereof, I hereunto subscribe my name this 5th day of AprilA. D., 1918. JOHN H. BELL.

